Telephone system.



E. R. HOBBS.

TELEPHONE SYSTEM. APPLICATION FILED MAY 15, 1909. v

1,025,269; Patented May 7, 1912.

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COLUMBIA PLANOORAPH c0..WA5IuNarnN D c UNITED STATES PATENT oFF oE.

ELBERT IR. HOBBS, OF BUHL, IDAHO.

To all whom it may concern:

Be it known that I, ELBERT R. Hours, a citizen of the United States,residing at Buhl, in the county of Twin Falls and State of Idaho, haveinvented certain new and useful Improvements in Telephone Systems, ofwhich the following is a specification, reference being had therein tothe accompanying drawing.

My invention relates to telephone sys tems, and has for its object theimprovement of the two-wire multiple circuit systems used in connectionwith a common battery at the central station. In ordinary circuits ofthis kind there are numerous objections and it is my object to overcomethese objections by a novel arrangement of the ap paratus comprising theoperators cord circuit and the parts constituting the subscribers lineterminal apparatus.

An object of my invention is to provide an efficient testing means sothat when a subscriber calls up the mere act of removing his receiverplaces his line terminals at once in condition for testing busy.

A further object of my inventionis to improve the calling end of theoperators cord circuit by providing a supervisory control relay, theserelays jointly controlling a test relay and the supervisory relay beingso arranged that it can pull up and look, thereafter being independentof the control relay.

A further object of my invention is to provide the line terminals withmeans whereby the positive operation of the calling supervisory relay iseffected.

Other objects and advantages will ap pear in the detailed description ofthe system as hereinafter set forth.

My invention is illustrated in the accompanying drawings in which:

Figure 1 shows the terminal apparatus of a subscribers line. Fig. 2 isan operators cord circuit arranged to cooperate with either of the lineterminals shown in Figs. 1 and 8. Fig. 3 is a modified arrangement ofthe subscribers line terminal apparatus. Fig. 4: is a modified form ofoperators cord circuit.

Referring to Fig. 1, I have shown therein the line wires 1 and 2 leadingfrom a subscribers substation (not shown), the sleeve side 2 of the lineterminating in contacts of the cut-off relay M, the tip side 1 of theline being connected to the jack J and being normally connected to thebattery B by the Specification of Letters Patent.

Application filed May 15, 1909.

TELEPHONE SYSTEM.

Patented May *7, 1912.

Serial No. 496,126.

branch 3 through the contacts 4 of the cutoif relay M and conductor 5.One winding of the cut-off relay M is connected with the extensionconductor 6 the other winding of the cut-off relay being connected tobattery through the resistance r. A normally closed shunt circuit isprovided around this resistance a" through the conductors 7 and 8 andthe armature 9 of the line relay R. The energization of the linerelaybreaks this shunt circuit and closes the circuit through the lampL. The operators cord circuit is provided with the usual plugs P and Pconnected on the tip side by the conductors 10 and 12 and on the sleeveside by the conductors 11 and 13. The condensers C and C are interposedon the tip and sleeve sides of the cord circuit to permit the passage ofvoice currents while cutting off battery currents. The answeringsupervisory relay R has one side of its winding connected to the tipconductor 10, the other side being grounded. The supervisory relay Rcontrols the circuit of the answering supervisory lamp S. The callingsupervisory relay R is connected to the tip side of the cord and itscircuit is controlled by the supervisory control relay R the winding ofthe latter being in series with the calling supervisory lamp S Theoperators set consists of the usual parts and includes the transmitter Tin circuit with the primary winding a of an induction coil. The receiverA is in circuit with the secondary windingc of the induction coiltogether with a condenser Q. This circuit is permanently connected tobattery and ground through high wound impedance coils, whose function isto keep the condenser Q, charged from the battery, thus providing a testby discharging therefrom through the tip side of the receiver circuit.As regards the busy test, after the operator has plugged into theanswering jack, it is understood that the potential of the sleeve of anidle line is the same as that of battery; when the operator plugs in,current will flow through the cutoff relay M, sleeve, and supervisorylamp, in series, and as the jack sleeve is between the cut-oil relay andthe supervisory lamp, the potential of the sleeve would be lowered. Alistening key K is provided by means of which the operator can listen into get the number wanted when a connection is desired. The ringinggenerator G is connected on one side to ground and on the other side toa contact adapted to be closed by a ringing key K onto the tip side ofthe cord circuit.

The arrangement shown in Fig. 3 is somewhat similar to that in Fig. 1.In this figure, however, the cut-off relay is provided with amake-before-break contact in order to render the system clickless. Thecut-off relay M is normally connected with the battery B through theresistance 1" and on the other side to the extension 6. The line wires 1and 2 terminate as in Fig. 1. The line relay R is provided with an extracontact for the purpose of keeping the circuit of the line wire 1 closedto ground until the relay R is connected. The line relay controls thecircuit of the signal lamp L as in Fig. 1.

The cord circuit shown in Fig. 4 is similar to Fig. 2, differing only inits test circuit which makes use of a test relay R This relay iscontrolled by contacts on the supervisory and supervisory-controlrelays, it being connected at one end through these contacts in series,to tip of calling plug, and at the other end to battery, thus providinga test to ground.

The operation of the system will be readily understood from theforegoing eX- planation of the apparatus used. Referring now to Figs. 1and 2, when a subscriber desires a connection he removes his receiverfrom the hook, thereby closing the circuit through the line wires 1 and2. The line relay R is energized, the energizing current flowing frombattery B, through 7, 9, R, 20, 21, 2, through subscribers instrument,back on line 1, 3, 4, 5, to ground. The actuation of the line relay Rcloses the circuit of the line lamp L at 22 and the lamp is lighted. Atthe same time through the pulling up of the armature 9 the shunt aroundthe resistance r is broken. On seeing the lighting of the signal lamp Lthe operator places the answering plug P in the jack J. If, however,before she has had time to insert the plug in its jack anothersubscriber should desire to communicate with the calling subscriber, asecond operator before whom the line of the second subscriberterminates, on testing the first subscribers line in the ordinary way,will find it busy even before the first operator has plugged in. Thesecond operator will get a click in the ear due to a discharge from thecondenser Q1, through A, 0, 26, 67, 28, 29, 79, through the-ring of thecalling subscribers multiple jack j 6, M, 8, 9, 22, L, and ground. \Vhenthe first operator plugs into the answering jack the cut-off relay M isat once energized, current flowing from battery B, through 7", M, 6, j p11, S, 31, 32 and to ground. The actuation of the cut-off relay placesthe line wire 2 onto its extension 6 and breaks the circuit through theline relay R at 33. On

the retraction of the armature 9 of the line relay R the shunt circuitaround the resistance r is again established. The energization of thecut-off relay permits the flow of current through the subscribersinstrument over the following path: battery 7, 9, 8, M, 34, 2,subscribers telephone, 1, j, p, 10, 85,

and ground. Thereupon the relay R pulls up and breaks the circuit of thelamp S. After plugging in to answer the call the operator presses herlistening key K and inquires the number wanted. Having obtained thenumber she tests the wanted line in the usual manner by touching the tipof the calling plug P to the ring of the jack. If the line is busy shewill get a click through the test set in the manner already described.If the line is not busy she inserts the calling plug P in the jack,presses the ringing key K ringing current being supplied to the linefrom the generator Gr over the following path: generator, 35, 29, j, 1,subscribers ringer, 2, (and since the cutoff relay has pulled up)through the extension 6, j 79 36, 37, and ground. It will be understoodthat the circuit just traced is through the called subscribers lineterminal apparatus. Since this is identical with Fig. 1 the latterfigure is intended to suffice as an illustration for both the answeringand calling subscriber, Fig. 3 being a modification of the subscribersline terminal apparatus as before stated. The energizing circuit of thecut-off relay of the called subscribers line is from battery B, 7, 9, 8,M, 6, 29 3c, 38, 13, S B 39, 40, 41, 42 and ground. The lamp S thereuponlights up. lVhen the called subscriber answers the supervisory relay Ris energized, the energizing circuit being from battery B, 7, 9, S, M,2, through subscribers instrument, 1, j, p, 29, 12, R 43, 44, 45, 46,42, ground. The actuation of the supervisory relay R breaks the circuitof the lamp S at 40, but before breaking the circuit it closes a lockingcircuit to ground at 47 through the armature 48. The battery supplycircuit of the calling subscriber is through the cut-off relay, throughhis instrument, back on the tip side of the line and through thesupervisory relay R, that of the called subscriber being through hiscut-off relay, over the line 2, through his instrument, back on the line1 and through the relay R to ground. When the subscribers hang up theirreceivers these circuits are broken. The supervisory relays R and R letgo, the supervisory lamps being lighted by a current over the sleeveside in the manner already shown. When the operator observes thelighting of the supervisory lamps he withdraws the plugs from theirjacks, the cut-off relays thereupon let go and the whole system isrestored to its normal condition.

Referring now to Fig. 3 I have shown therein a modification of thesubscribers line terminal apparatus. In this figure, which is to betaken with the cord circuit shown in Fig. 2, the line relay R isoperated when the receiver is removed from the hook,

current flowing from battery through 7, 9', R, 20, 21, 2, subscribersinstrument, 1, 3, 4, 5 and to ground. This closes the lamp circuit inthe manner described in connection with Fig. 1 and also puts a ground onthe line wire 1 through the closure of the con tacts 50-51 and throughthe shunt 52. When the operator plugs in in response to the call, thecut-off relay is energized and current flows from battery B over thesleeve side 2 of the subscribers line and back upon the tip side 1through the relay R of the answering end of the cord circuit, but sincethe relay M is provided with the makebefore-break cont-act there oughtto be no click when the plug is inserted. The testing and ringing areaccomplished with the arrangement shown in Fig. 3 in the mannerdescribed in connection with Fig. 1. When the operator inserts thecalling plug P in the jack, the cut-ofi" relay M of the calledsubscribers line, puts the line wire 2 onto its extension 6. At the sametime the movement of the armature 4: cuts the line wire 1 oif fromground. In order to keep ground on the line 1 until the relay R has hadtime to pull up, I have provided the shunt circuit 52 already described.This shunt circuit is closed by the line relay R which is controlled bythe cut-01f relay M. Since the cut-oii relay has the make-before-breakcontact and since there are two relays to operate before the ground istaken oii from the line wire 1, it will be apparent that the supervisoryrelay B will have time to act. When conversation has ended and thesubscribers have hung up their receivers the supervisory relays aredeenergized, the supervisory lamps light up and the operator withdrawsthe plugs, thereby restoring the system to its normal condition.

Having thus described my invention, what I claim and desire to secure byLetters Patent of the United States is- 1. In a telephone exchangesystem, subscribers lines provided with terminals, an operators cordcircuit provided with an answering supervisory relay on one end thereofand a calling supervisory relay and a control relay on the other end, atest coil controlled by contacts on said calling supervisory relay andsaid control relay, means for testing by current in one direction by thecut-off relay and means for supplying current for talking purposesthrough the cut-01f relay in the opposite direction.

2. In a telephone exchange system, subscribers lines provided withterminals, an operators cord circuit provided with an answeringsupervisory relay on one end thereof and a calling supervisory relay anda control relay on the opposite end thereof, and a test circuitcontrolled by said calling supervisory relay and control relay jointly.

3. In a telephone exchange system, a subscribers line provided with aline and a cut-off relay the latter relay being normally connected tobattery through a resistance coil, a shunt circuit around said coilcontrolled by said line relay, means for testing the lines by currentthrough said cut-oft relay in one direction and means for supplyingcurrent for talking purposes through said cut-off relay in the oppositedirection.

at. In a telephone exchange system, subscribers lines provided withterminals, an operators cord circuit, answering and calling supervisoryrelays therefor, a control relay for'the calling supervisory, a signallamp arranged in series with said control relay and locking means onsaid calling supervisory relay.

5. In a telephone exchange system subscribers lines provided withcut-ofi relays, line relays and signal lamps, an operators cord circuitprovided with a test coil, means for testing said lines by currentthrough said test coil, said cut-oif relay and said line lamp, togetherwith means for supplying talking current in the reverse directionthrough said cut-off relay.

6. In a telephone exchange system, subscribers lines provided withcut-0E relays, line relays and line signals, an operators cord circuitprovided with answering and calling supervisory relays and a controlrelay for said calling supervisory relay, said control relay beingnormally grounded on one side, a test coil controlled conjointly by saidcalling supervisory relay and said control relay, and means forsupplying current through said cut-off relay in one direction for testpurposes and in the opposite direction for talking purposes.

, In testimony whereof I aflix my signature in presence of twowitnesses.

ELBERT R. HOBBS.

Witnesses:

J OHN W. FAnIs, WALTER Gr. BISHOP.

Copies of this patent may be obtained for five cents each, by addressingthe Commissioner of Patents, Washington, D. G.

